Magnetic Moments in Single-Atom Alloys: Trends, Mechanisms, and Implications for Tunable Adsorption.

Single-atom alloys have proven to have promising and unusual catalytic, chemical, and electronic structure properties. However, the mechanism underlying their magnetic states and the effect of these states on their chemical and catalytic properties are not well understood, despite the demonstrated importance of magnetism in catalysis. Here, we study the magnetic states of single-atom alloys consisting of transition metals embedded in Cu, Ag, and Au hosts. We find that many single-atom alloys feature strong magnetic moments, associated with large energetic differences between spin-polarized and nonspin-polarized states as well as large effects on adsorption energies. Indeed, the magnetic moment linearly correlates with the effect of the spin on adsorption. The Stoner criterion is generally quite accurate in predicting whether magnetism occurs. The shift of the d-band center roughly correlates with the change in the adsorption energy upon inclusion of spin, although changes in the charge on the dopant atom also play a role for Ag-host single-atom alloys. This work opens pathways to leverage magnetic properties in single-atom alloys, including by the static modification of reactivity, dynamically programming energetics, or local magnetic heating at the single-atom site.